In a mining or construction operation, many different tools are ordinarily needed to complete the project. For example, there may arise a need for using a different sized bucket or exchanging a bucket for an impact hammer. To minimize the number of carriers at a job site, a single carrier is often used to support and operate a number of different tools. In the present application, only the use of a backhoe is discussed for the purposes of illustration. Nevertheless, other carriers are also used in similar ways.
A typical backhoe comprises a moveable vehicular portion and an elongated, articulated boom. The boom is comprised of a number of pivotally interconnected arms moved and controlled by a series of hydraulic cylinders. The arm defining the free end of the boom is commonly referred to as the stick. The stick defines a transverse bore on its free end for receiving a mounting pin. The mounting pin is further received through corresponding holes in the tool to pivotally secure the tool to the stick.
A box end linkage is also typically provided along the free end to support and move the tool as desired. Specifically, a box end linkage is comprised of a pair of articulated links, wherein one of the links is pivotally attached to the stick, one of the links is pivotally attached to the tool, and the two links are pivotally attached to each other. A hydraulic cylinder is pivotally coupled to the links at the point of their interconnection with each other. As the hydraulic cylinder is expanded and retracted, the tool is rotated about the mounting pin connecting the tool to the stick. Alternatively, the hydraulic cylinder is at times attached directly to the tool, thus omitting the box end linkage. While the operation of the tool is substantially the same in this alternative construction, the range of pivotal movement and curling force are significantly reduced.
To accommodate the mounting of the tools to the boom, all of the tools are generally provided with a common mounting arrangement. Ordinarily each of the tools are provided with a pair of upstanding flanges spaced apart to define a gap into which is received the ends of the stick and the linkage. The flanges are each provided with a pair of spaced apart bores for receiving the tool mounting pins. Although the use of two mounting pins is common, more than two could also be used. As can be appreciated, alignment and installation of the mounting pins in the field is an onerous and time consuming task. Moreover, due to the tight fit of the pins, their removal can also be difficult to achieve.
In view of the need to interchange tools on a carrier, many quick coupling devices have been developed to ease and speed the installation and removal of the tools in the field. In general, most of the quick coupling devices are designed to quickly and easily engage and attach to the mounting pins which extend across the upper portion of the tools. Although many different constructions have been developed, a common quick coupling device includes notches adapted to receive one of the mounting pins and a second mechanism adapted to receive and secure the other of the mounting pins. With this arrangement, the tools are securely locked to the quick coupling device. Examples of this type of construction are shown in U.S. Pat. Nos. 4,810,162 to Foster, 4,355,945 to Pilch, 4,295,287 to Natzke et al. and 4,187,050 to Barbee.
The quick coupling devices of the prior art have reduced the time and effort otherwise needed to exchange tools on a carrier. Nevertheless, the quick coupling devices of the prior art are designed to engage only those tools having mounting pins which are spaced apart a specific distance. Unfortunately, in practice, all tools do not have a uniform spacing between the mounting pins. In such cases, the operator is forced to either not use the quick coupling device in regard to these tools or have additional quick coupling devices available to accommodate pins of different spacings.
Additionally, due to the affects of wearing and differences in manufacturing tolerances, the quick coupling devices often loosely grip the tool to be operated. Such looseness in the connection not only causes the tool to suffer premature wearing, but also increases the risk of an unintended release of the tool. As can be appreciated, this can create a very dangerous situation for the workmen involved. In regard to certain tools, such as an impact hammer, the looseness in the connection can also hamper the ability of the operator to properly position the tool.